Strictly speaking, there is a defined game term of True Dragon in Draconomicon. It's fairly obviously intended as such.
That said, fluff on what happens to be a true dragon IS very subjective. There's a *lot* of draconic stuff, and stuff that's trying to be draconic. Which one is 'true' is debateable. Certainly, Dragonwrought kobolds have pages of fluff about just how danged draconic they are.
Banning it because it's too high powered for a campaign is quite reasonable, but calling it "common sense" really seems to be just looking for a justification for something you're just doing for balance reasons.
I also agree on all of this. Things like drowning not healing you? Common sense. We all agree that shouldn't work. The only possible objections are phrasing issues, or other things of that nature*.While I agree that there are corner cases, the fact that there are a number of rules with 30%-70% means that there is no RACSD, unless you're going to use a very strange definition of "common sense." I'll use Rule 030 as an example. As near as I can tell, there is no RAW on this, since the designers didn't seem to grasp that you could shapechange between a blue dragon and a red dragon. Similarly, there is no RACSD, as evidenced by the 30/70 split in voting.
In addition, as Tuggyne pointed out earlier, how a DM rules on cooldown is going to depend almost entirely on how they conceive of magic working in their world. Unlike, say, drowning to stabilize someone or whether you can replace the boots that come with full plate, it is something that almost always impacts the game world and not just the game.
Things that are "I don't like this because I don't believe it's balanced" are not the same as common sense. Is a candle of invocation to get a genie balanced? God no. But saying it's "common sense" to work differently is just slapping a weak justification on your rules change instead of admitting to the real one. I see a lot of rules in here as the same sort of thing.
*Strictly speaking, I see it as entirely redundant, since Stormwrack already fixed this officially.